Method of making a safety shield for electric heating mantle



Jan. 28, 1969 a. H. MOREY 3, 7

METHOD OF MAKING A SAFETY SHIELD FOR ELECTRIC HEATING MANTLE Original Filed Jan. 18, 1962- Sheet of 2 llb //o\ 42 I a 3 I 4a l E m m I l l i I l l/ l INVENTOR.

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United States Patent 3,424,637 METHOD OF MAKING A SAFETY SHIELD FOR ELECTRIC HEATING MANTLE Glen H. Morey, Terre Haute, Ind., assignor to Templeton Coal Company, Terre Haute, Ind., a corporation of Indiana Original application Jan. 18, 1962, Ser. No. 167,108, now Patent No. 3,177,343, dated Apr. 6, 1965. Divided and this application Dec. 5, 1962, Ser. No. 242,473 U.S. Cl. 156-242 1 Claim Int. Cl. B2911 31/00; B29c 17/02 ABSTRACT OF THE DISCLOSURE A method for making a flexible fluid-impervious shield for a flask in which high temperature textile material is worked smooth on a form, clamped at its margin to the form, and coated on the form with a coating composition. The coating composition is then cured, the shield is removed from the form, the uncoated margin is trimmed off, and a hole for the flask neck is then formed in the shield at the appropriate place.

This present invention relates to a safety device for use in connection with containers such as glass flasks and glass beakers and the like, and is particularly concerned with a method of making such devices.

The present application is a division of my copending application Ser. No. 167,108 filed Jan. 18, 1962, entitled Safety Shield for Electric Heating Mantle, and now Patent No. 3,177,343.

As brought out in my copending application referred to above there are many chemical operations, in particular in connection with laboratory work, wherein materials are placed in glass containers and heated therein. These liquids are often inflammable or give off explosive vapors; and, a preferred manner of heating the containers with such liquids is by means of an electric heater which not only provides for nicety of control of the temperature and is convenient, but also with much less danger of fire and explosion.

Electric heating devices of this nature often take the form of a heating mantle which consists, basically, of a heat resistant fabric to which is secured an electric resistance heating element with the fabric being generally fitted to the configuration of the container. The container is placed in the mantle and rests on the fabric, and this will bring the electric heating element carried by the fabric into eflicient heat transfer relation with the container.

While this manner of heating a container greatly minimizes the hazards referred to above, the liquid in the container will sometimes boil over or will foam up and spill out over the top of the container, or liquids may be spilled while pouring them into the container so that there can also be spillage of liquids on the outside of the container which might cause breaking of the container and which could get on the heating mantle and cause damage thereto. Still further, if the liquids are inflammable or explosive, they could create a dangerous fire or explosion.

With the foregoing in mind, I have devised a relatively simple device and a relatively simple but highly effective and efficient method in making the device which will protect flasks and beakers and the like from the danger of liquids being spilled on the outside thereof, and which safety device can also confine the heating mantle to exclude therefrom corrosive, inflammable, and explosive vapors that might be developed.

It is accordingly a primary object of the present in- 3,424,637 Patented Jan. 28, 1969 vention to provide a method of making an improved safety device of the nature referred to.

Another object of this invention is the provision of the method of making a relatively inexpensive safety device of the nature referred to according to which the device can be made of substantially any size or configuration.

A still further object of this invention is the provision of a method of making a safety device of the nature referred to which has a fabric base and a rubber-like sealer 0n the base and according to which method the device when manufactured, regardless of the configuration, will be free of wrinkles.

These and other objects and advantages of the present invention will become apparent upon reference to the following specification taken in connection with the accompanying drawings in which:

FIGURE 1 is a perspective view showing a heating device for a flask, and a flask therein and a protective shield according to this invention;

FIGURE 2 is a side elevational view of the arrangement of FIGURE 1 showing more in detail the nature of the shield and also showing the heating device partly in section;

FIGURE 3 is a view similar to FIGURE 2 but which shows how the device according to the present invention could be modified to accommodate a flask having a plurality of necks;

FIGURE 4 is a fragmentary view showing a modified arrangement of a sight glass in the shield;

FIGURES 5 through 9 diagrammatically illustrate steps that are carried out in connection with the manufacture of a shield according to the present invention;

FIGURE 10 is a fragmentary sectional view indicated by line 1010 on FIGURE 9;

FIGURE 11 is a sectional view of a somewhat modified arrangement for constructing a shield;

FIGURE 12 is a view showing the completed shield; and

FIGURE 13 shows a modification.

Referring now to the drawings somewhat more in detail, a typical installation in connection with which the present invention can be practiced consists of a flask heater 10 having a flask 12 therein. The flask heater 10 comprises a metal frame 14 and mounted in the frame is a high temperature resistant fabric mantle 16 adapted for receiving and supporting the flask 12. This mantle 16 has an electric heating element 18 stitched thereto on the side opposite the flask and to which heating element electrical energy is conducted through cord 20.

In this manner, the flask can be heated to any desired temperature and maintained at that temperature.

It will be evident, particularly, on reference to FIG- URE 2, that any spillage, or foaming over, or boiling over of liquids at the top of the neck 22 of the flask will cause liquids to run down the outside of the flask and which liquids would fall directly on the heating mantle. This is dangerous on account of damage to the mantle and on account of the possibility of fire, or explosion, or the development of toxic vapors.

According to the present invention, the possibility of liquids coming into contact with the heating mantle is substantially eliminated by the provision of a substantially hemispherical shield generally indicated at 24 and which is so constructed as to engage the top of the frame 14 of the heating unit and about the neck of the flask being heated.

This shield is made of a rubberlike material, such as synthetic rubber or an elastomeric plastic, and is capable of withstanding temperature, preferably, up to 500 degrees F.

Among the materials which can be employed for this purpose is silicone rubber, but still other materials would suggest themselves to those skilled in the art.

The device consists of a substantially hemispherical body portion 26 with a central opening therein which resiliently embraces the neck of the flask in the region of the base thereof. The periphery of the hemispherical body portion is adapted for engaging about the top of the body 14 of the heating device and, to this end, preferably includes a reinforcing rib 30 so that the shield will engage the body of the heating device under sufficient tension to hold it tightly thereon.

The material of the shield is elastic, at least in the regions that engage the neck of the flask and the frame of the heating device and thus a substantially liquid tight, vapor-tight engagement of the shield with these elements is had. In addition to forming a liquid and vapor excluding shield about the upper portion of the flask and the open upper side of the heating device, the shield forms a dead air space 32 about the top of the flask and this inhibits the loss of heat from the flask, thus making for more eflicient operating conditions.

The shield also provides a substantial degree of protection against accidental tilting of the flask because, with a round bottom flask resting in the fabric mantle, the flask can quite easily be tilted, and the shield of the present invention provides substantial support against such accidental tilting.

Still further, on account of the space between the shield of the present invention and the flask, and on account of the lower specific heat of the material, and in view of the dead air space between the shield and the flask, there is little chance of anyone becoming burned on account of touching the shield even though it is at substantially the same temperature as the flask.

The shield, according to the present invention, could be provided with a sight hole 34 which could be covered by a transparent material as at 36 so that the flask could be observed even through an opaque shield. Even if the shield were of a transparent nature, it would still be advisable to put a sight hole therein for easy observation of the flask. This sight hole has been indicated as being covered by a thin transparent member, but it will be understood that the shield could be so formed that a heavier member could be placed therein, if so desired, for example, a glass disc.

FIGURE 4 shows one manner in which this might be done. In this figure, there is a sight glass 38 and it is snapped into a groove 40 provided in the shield for this purpose. Such arrangements are well known in connection with swimming masks.

In FIGURE 3, I show how a flask having more than one neck as, for example, at 42, 44 and 46 could receive a shield 48 according to this invention merely by providing the shield with openings at 50, 52 and 54 for receiving the necks. It will be observed that in all of the modifications, the neck portion is either somewhat reinforced or has a short flange means 56 thereon in order to insure proper sealing engagement of the shield with the neck of the flask.

The shield arrangement described above employs a rubberlike material, such as elastomeric silicone rubber.

FIGURES through 12 illustrate shields and methods of making the same which permit the shield to be made as small or as large as desired.

In FIGURE 5 there is a hemispherical form 100 having flange 102 at the bottom. Arranged on this form is a relatively loosely woven fabric 104, which may advantageously be a glass fabric, for example. The fabric is loosely woven and where the filaments are smooth and slippery, as with glass or synthetic filaments, the fabric can easily be worked around on the form to eliminate wrinkles and to form a smooth envelope over the form. The bottom periphery of the fabric may be fixed in place on the form as by clamping a ring 106 on the flange of the form with the margin of the fabric therebetween.

This will hold the fabric tight and smooth on the form.

FIGURE 6 shows a plastic composition 108 being poured on the fabric. This plastic composition may, for example, comprise a silicone rubber composition having a curing agent therein so that the material will cure on the form and so that no heating of the form is absolutely required. This material is readily flowable so that it will tend to flow down about the fabric on the form and to penetrate and impregnate the fabric.

The material is troweled as by trowel 110 so as to provide a continuous smooth layer over the fabric and with the material in this condition it will then cure and set up on account of the curing agent therein, and the form and the shield mounted thereon will have somewhat the appearance that it has in FIGURE 8. The workpiece can be air cured in about 24 hours, or it can be oven cured at about 200 degrees to 400 degrees F. in about 15-30 minutes.

After the workpiece is completely cured it can be removed from the form and one or more apertures 112 can be formed therein. This process enables shields of any size, or of substantially any configuration, to be manufactured rapidly and economically and without any great investment in tools.

The appearance of the shield in cross section is illustrated in FIGURE 10, wherein it will be seen that the fabric 104, which may consist of one or more layers of material, is completely coated and impregnated with the rubberlike material 108. The shield is thus quite strong and is also liquid tight, and has all the characteristics with respect to resistance to chemical attack, abrasion, and the like, that is exhibited by the rubberlike material.

The embodiment of FIGURES 11 and 12 introduces the possibility of providing the form 114 with an adapter member 116, which can be located to form the aperture for the neck of the flask, or there can be more than one of the adapter members 116 provided to afford apertures for a multineck flask.

The same process as described above is carried out with the embodiment of FIGURES 11 and 12 and the result is the same excepting that the resulting shield has one or more apertures 118 integrally formed therein, so that no cutting of the finished shield is required.

In either case it is preferable to cement a resilient ring about each aperture which is to receive a neck so good sealing engagement will be had with the neck.

The shields according to my invention have been exhaustively tested, for example, by subjecting the shield to assembly while the electric heating element is operating under full power, with the flask containing boiling water, by showering the shield of the device for long periods of time with ether and gasoline and acetone. No fire resulted in these prolonged tests, thereby indicating the efliciency of the shielding device according to my present invention. Further, there was no visible deterioration of the shield.

With respect to the plastic mixture that is employed in the modifications of FIGURES 5 through 12, the following example is given merely as a single example and is not to be considered in any way restrictive to the scope of the appended claim.

A liquid silicone rubber composition sold under the name of Dow-Corning RTV 601 is mixed with a catalyzer and this forms the rubberlike material for making the shield. The material has a working life of about six hours and will set up in air in about 24 hours or can be oven cured in about 15 minutes at about 200 degrees to 300 degrees F.

Small shields lend themselves to oven curing and very large shields would probably be air dried.

FIGURE 13 shows, somewhat schematically, how the present invention can be adapted to containers other than flasks; beakers, for example.

In FIGURE 13, the electric heating mantle is diagrammatically illustrated at 110 and a container, such as a glass beaker 112, is supported therein. Extending over the top of the mantle 110 and around beaker 112 is a flexible web element 114 which may be of rubberlike material, either with or without textile reinforcng. Alternatively, the web may be a textile like material impregnated or coated with a rubberlike sealer. In either case, the web is fluid impervious and will deflect spilled liquids from the upper open end of the heating mantle.

The web element preferably has integral therewith, or attached thereto, elastic bead portions 116 around the mantle frame, and 118 around the container. These beads cause the edges of the web to grip the mantle frame and the beaker to form a substantially liquid tight and vapor tight but easily releaseable engagement of the web with the mantle frame and container.

It will be appreciated, from the foregoing, that the shield of the present invention has wide application to various containers.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions; and, accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claim.

I claim:

1. A method of making a flexible, elastic, fluid-impervious and heat-resistant shield adapted to fit over the body portion of a flask which is seated on an electric heater and also over the upper periphery of the latter, said shield being made by applying a loosely woven heat-resistant fabric over a rigid hemispherical form and around the periphery of an upwardly projecting adapter member that is carried centrally at the top of the form while smoothing out Wrinkles in the fabric, clamping the periphery of the fabric to the periphery of the form, applying a curable but permanently flexible and elastic heat-resistant coating and impregnating composition to the fabric While it is on the form, said composition being applied in a layer UNITED STATES PATENTS 2,008,136 7/1935 Gonyer 1562l2 XR 2,533,474 12/1950 Koch 156-l08 XR 2,919,218 12/1959 Le May 156-212 2,951,277 9/1960 Youngs 156162 XR 3,170,828 2/1965 Irvine 156212 2,842,654 7/1958 Anderson 219-433 2,945,114 7/1960 Mathews 219385 2,422,266 6/ 1947 Steinke 18-59 2,858,572 11/1958 Burdick 1859 3,177,343 4/1965 Morey 219-433 OTHER REFERENCES Sonneborn, Ralph H.: Fiberglas Reinforced Plastics, Reinhold Pub. Corp, New York, 1954, pp. 66-67.

Kauppi, T. A.: Silicones, Modern Plastics Encyclopedia for 1959, Modern Plastics Magazine, New York, September 1958, pp. 149-152.

EARL M. BERGERT, Primary Examiner. R. A. KILLWORTH, Assistant Examiner.

US. Cl. X.R. 

